A GOA technology, namely Gate Driver on Array is a technology in which gate drive circuits (Gate Driver ICs) are directly manufactured on an array substrate (Array); instead of external silicon wafer connected thereto. Due to the application of this technology, the gate drive circuit can be directly processed on the periphery of a panel, thereby reducing the making procedures and lowering the product cost. In addition, the high integration of a TFT-LCD panel is further improved, to make the panel thinner.
However, in the two-level driving, among a variety of different feed through voltages, the feed through voltage generated by Cgd is dominant. Therefore, in the case of the two-level driving, the voltage of a common electrode needs to be regulated, in order to improve the gray scale quality.
When the common electrode COM is driven by direct current DC, the feed through voltage across the Cgd is:(Vg_high−Vg_low)*Cgd/(Cgd+Clc+Cs),
wherein Vg_high and Vg_low represent respectively voltages for opening and closing the wires of the gate drive circuit, and Cgd, Clc and Cs are respectively parasitic capacitance of TFT, liquid crystal capacitance and storage capacitance.
Since the feed through voltage is mainly caused by pull down of a pixel voltage by change of a gate voltage in the case of TFT closing by means of the parasitic capacitance Cgd. No matter the pixel voltage is positive or negative, the feed through voltage will always pull the pixel voltage down to be negative.
In the prior art, the impact from the feed through voltage can be reduced by compensating the voltage of the common electrode. But since Clc is not a fixed parameter, the impact from the feed through cannot be eliminated by regulating the drive voltage of the common electrode, such that the objective of improving the image quality is difficult to achieve.
At present, a simple and feasible GOA circuit design needs to be provided to reduce and even eliminate the feed through voltage, so as to improve the gray scale quality of the display.